There is not a 1:1 correspondence between Whonix & Qubes versions nor are Whonix templates customized for individual Qubes versions. I believe the Whonix policy is to support all Qubes supported versions, so Whonix 13 currently supports R3.2 and R3.1.

As is touched on in the post linked above, the Whonix version numbers in Qubes-Whonix are fairly meaningless. I know of no easy way to map between the Qubes-Whonix version numbers and the corresponding Whonix version numbers. Instead, you can check the Whonix column in the TemplateVMs table on the Supported Versions Qubes Documentation Page to see which version of Whonix your version of Qubes supports.